Electrical contact and the manufacture thereof



March 7, 1933. J A. marra `,9o,256

ELECIRICAL CONTACT AND THE MANU FACTURE THEREOI'" Filed Feb. 25, 1932 2' Shets-Sheet 2 Patentecl Mar. 7, 1933 UNITED STATES PATENT OFFICE JOSEPH ARTHUR PAYETTE, OF ,ATTLEBORQ MASSACHUSETTS, ASSIGNOR TO GEN'EBAL PLATE COMPANY, OF ATTLEBORO, MASSACHUSETTS, A COBPOBATION' OF MASSACEU- t SETTS ELEOTRICAL CONTACT AND 'THE MANUFACTURE THREOF Application filed February 26, 1932. Serial No. 595365.

This invention relates to electrical contacts, and With regard to certain more specific features, to c'ontacts for use especially with thin blade material.

Among the several obj ects of the invention may be noted the provision of an electrical contact of the class described which includes a reduced quantity of precious metal, without, however, decreasing the Contacting area of such metal; the provision of a contact of the class described which eliminates the necessity of vpunching, riveting, and like operations r'or aflixing precious metal to the thin blade material; `a contact of the class de scribed wherein the precious metal issecurely aflixed to the thin blade material; a contact of the class described wherein the precious metal is maintained in improved electrical contact relationship with the thin blade material; the provision of a method of manufacturing contactsof the class described v wher-ein only simple Operations, such as rolling, pressing and the like are involved; and the provision of a contact and a method of manufacturin the same which is economical and simple. ther objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, steps and sequence of steps, features' of construc-. tion and synthesis, and arrangements of parts, which will be exemplified in the structures and processes hereinafter described, and the scope of the a plication of which will be indicated in the ollowing claims.

In the accompanying drawings, in which are illustrated several of various possible embodiments of the invention,

Fig. 1 is an enlarged cross section of a sheet 4 terial after the operation indicated in Fig. 4 has been performed thereon;

Fig. 6 isa bottom plan View of the blade material after the operation indicated in Fig. 4 has beenperformed thereon;

Fig. 7 is a cross section illustrating the first step in the application of precious metal to the blade material;

Fig. 8 is a cross section similar to Fig. 7 illustrating the final positioning of the precious metal on the blade material;

Fig. 9 is a top plan view of the assembly illustrated in Fig. 8;

Figi. 10 is a trinetric View of a completed thin lade contact;

Fig. 11 is a View similar to Fig. 5 illustrating an alternative embodiment of the inven ton; v

Fig. 12 is a cross section similar to Fig. 8 illustrating another embodiment of the invention; and,

Fi 13 is a 'cross section similar to both Figs. 8 and 12, illustrating yet another embodiment of the invention.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

The heretofore-used Construction of thin blade Contacts, which comprises, generally, the riveting of a heavy rivet of -precious metal into the end of a thin blade, is disadvantageous in several respects. In the first place, only a relatively small area of good electrical contact is Secured between the precious metal rivet and the thin metal blade, thus decreasing the electrical conducti-vity. Tn the second place, in order to`dissipate heat, t is necessary that a heavy rivet be used, and this requires a considerable amount of precious metal in the rivet, thus increasing the cost considerably; In the third place, the rveting operation is uneconomical and impractical. In the fourth place, the loosening of the rivets, which takes place during use, permits oxidation to enter between the rivet and the strip, causing overheating and frequently total destru'ction of the contact.

The present inventio'n overcomes all of the foregoing difficulties, and provides a thin blade contact wherein the maximum area of contact is provided between the precious metal and the thin blade, thus increasing the electrical conductivity of the assemhly, and at the same time permits the use of the precious metal in strip or sheet form, or as a composite metal comprising base metal and a relatively thin layer of precious metal, without necessitating the specialized preformation of rivets therefrom.

Referring now more particularly to Fig. 1, there is illustrated at numeral 1, in considerably enlarged form, a sheet of thin-blade material. The material 1 usually comprises a spring bronze or the like but might equally well be any other good electrical conducting metal, such as spring Copper, brass, or the like.

The first operation of the present invention comprises turning over or rolling the edge of the sheet 1 to form a bead or overlap 2 (see Figs. 2 and 3). It will be understood that this operation may easily be performed either With dies or rollers or the like, and is comparatively simple to carry out.

After the head 2 has been formed on the sheet 1 it is passed through a pair of rollers or the like which are so formed to provide a series of indentations or depressions or the like 3 on either or both sides of the head 2. Figs. 5 and 6 illustrates the conformation of such indentations on the top and bottom sides of the sheet l. Instead of the simple, corrugated form of indentations 3, the rolls may be arranged to produce a knurling or the like such as illustrated in Fig. ll. Any suitable conformation may be used, the purpose of the indentations 3 being merely to supply a firm holding region for the precious metal later to be applied.

With the sheet 1 prepared as in Fig. 4, the next step comprises the aing of the precious metal contact material Such precious metal contact material is Originally provided in the form of a strip which is bent to a U- conformaton illustrated at numeral i in Fig. 7. The precious metal a is placed in position around the head 2 as illustrated in Fig., 7 and then passed through a pair of compression rollers or the like. The efiectoi the compression rollers is to cause the precious metal 4: to flow into the indentations 3 and to surround the head 2 in such a manner that the precious metal i secures itself to the sheet 1. The final position of the precious metal is illustrated in Fig. 8. The shoulder formed by the edge of the head 2 indieated at numeral 5, prevents the precious metal l from beingpulled e& the sheet l, while the indentations 3 keep such precious metal from moving laterally on the sheet i.. 'lhus the precious metal is thus securely axed to the strip without soldering or the like, and without necessitating a riveting or lile procedure.

Fig. 9 is a plan view of the finished contact material illustrated in Fig., 8,. This matemo es@ rial is a blank from which the contact strips are cut, as along the dot and dash lines ndcated by numeral 6. The final form of an individual Contacting strip is illustrated in Fig. 10.

It will be seen that an electrical joint of high conductivity is achieved, because the area of contact between the precious metal 4: and the strip 1 is quite large. Further, the

joint is of a permanent, reliable nature, thus which the precious contact portion proper comprises a soft bronze or likelayer ;7 on which has been plated or rolled or otherwise axed a thin layer 8 of contact metal such as silver. In this instance, as in the others, the Contacting material is securely afixed with large conductive area to the strip or sheet 1.

Fig. 13 illustrates an embodiment somewhat similar to the embodiment of Fig. 12. In this instance, the precious metal plated area is confined to one side of the contact, as at numeral 9, and the quantity of precious metal (and total cost) is therehy reduced. Inasmuch as most Contacts are used on but one side, this Fig. 13 embodiment is the most practical, commercially, of the several emhodiments illustrated.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attainedh As many changes could be made in ing out the above constructions without departing from the scope of the invention, it is intended that all'matter contained in the above description or shown in the accompanying drawings shall he interpreted as illustrative and not in a limiting sense.

l claim:

l., An electrical contact comprising a blade of relatively thin metal, said hlade heing turned over at one end forming a head, and a metal contact of U-conformation, compressed around said head.,

. 2,. An electrical contact comprising a hlade of relatively thin metal, said hlade havin a head at one end thereof, said head having indentations thereon, and a, metal contact of U-conformetion surrounding said head and extending into said indentations.,

3. An elcctrical contact comprising a hlade It will of course be understood that' of relatively thin metal, said blade having a bead at one end thereof forming a 'shoul er, said bead having indentations thereon, and a metal contact of U-conformation surrounding said bead, said contact being compressed behind said shoulder, whereby relative mo-- tion lengthwise of the blade is rohibited, and into said indentations, where y relative motion crosswise of the blade is prohibited.

4. .An electrical contact as set forth in claim 3, in which the indentations comprise corru ations crosswise of the bead.

5. eiectrical contact as set forth in claim 3, in which the indentations comprise knurlings.

. a base metal having a layer of precious metal on one of its exterior surfaces.

10. The method of securing precious metal or like Contacts to thin blade material which comprises forming a head along one side of y the blade material, forming a series of indentations in said head, positioning a strip of reciois metal of U-conformation around sai bead, and compressing said strip until 'it flows around said bead and into said indentations.

In testimony whereof, I have signed my name to this specification this 8th day of February, 1932.

J OSEPH ARTHUR PAYETTE. 

